Spatial subsidies and indirect effects in subarctic food webs

亚北极食物网的空间补贴和间接影响

• 批准号: 386704-2010
• 负责人: Roth, James
• 金额: $ 1.82万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2010
• 资助国家: 加拿大
• 起止时间: 2010-01-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=463914
• 关键词: Spatial; subsidies; indirect; effects; subarctic

Interactions between predators and their prey are often affected by the presence and density of other species in the community. Species that share a predator can affect each others' abundance indirectly through changes in predation by the common predator. My research program seeks to understand such indirect interactions in food webs, particularly how interactions between predators and their prey are affected by alternative food sources. I am particularly interested in understanding these indirect effects when populations fluctuate in regular cycles, and when the alternative food source for a terrestrial predator comes from the marine environment. Arctic foxes often increase predation pressure on geese when their primary prey, lemmings, decline. Arctic foxes in winter and spring also feed on seals on the sea ice and can increase in abundance when seal availability and polar bear body condition (reflecting accessibility of seals) are high. Whether increased predation by arctic foxes subsidized by seals can suppress lemming populations or goose reproduction remains to be tested. This research will investigate how changes in the marine environment (seals and polar bears) affect terrestrial herbivores (geese and lemmings) through predation by arctic fox on the west edge of Hudson Bay in northern Manitoba. We will monitor annual changes in arctic fox abundance through den surveys in summer, seal availability through aerial surveys on the ice in spring, lemming abundance using mark-recapture methods, and egg predation on geese using nest surveys. Changes in diets of lemmings and foxes will be determined through stable isotope and fecal analysis, and any cascading effects of lemmings on tundra vegetation will be determined using exclosures. As the climate warms and sea ice declines, this research will seek to understand how a decline in marine resources may affect terrestrial herbivore productivity and dynamics of cyclic lemmings. As predation and herbivory are key ecological processes structuring ecological communities, the research described in this proposal (in collaboration with other long-term research in the area) will provide information fundamental to understanding the food web interactions in the subaractic.

捕食者和猎物之间的相互作用常常受到群落中其他物种的存在和密度的影响。共享捕食者的物种可以通过共同捕食者捕食的变化间接影响彼此的丰度。 我的研究项目旨在了解食物网中的这种间接相互作用，特别是捕食者和猎物之间的相互作用如何受到替代食物来源的影响。我特别有兴趣了解当种群数量定期波动以及陆地捕食者的替代食物来源来自海洋环境时这些间接影响。当鹅的主要猎物旅鼠数量减少时，北极狐常常会增加它们的捕食压力。冬季和春季的北极狐也会以海冰上的海豹为食，当海豹的可用性和北极熊的身体状况（反映海豹的可接近性）较高时，北极狐的数量会增加。海豹资助的北极狐捕食增加是否会抑制旅鼠种群或鹅的繁殖仍有待检验。这项研究将调查海洋环境（海豹和北极熊）的变化如何通过马尼托巴省北部哈德逊湾西缘的北极狐的捕食影响陆地食草动物（鹅和旅鼠）。我们将通过夏季的巢穴调查来监测北极狐丰度的年度变化，通过春季对冰面的空中调查来监测海豹的可用性，使用标记重捕获方法来监测旅鼠的丰度，并使用巢调查来监测鹅蛋的捕食情况。旅鼠和狐狸的饮食变化将通过稳定同位素和粪便分析来确定，旅鼠对苔原植被的任何级联影响将通过排除来确定。随着气候变暖和海冰减少，这项研究将试图了解海洋资源的减少如何影响陆地食草动物的生产力和周期性旅鼠的动态。由于捕食和食草是构建生态群落的关键生态过程，因此本提案中描述的研究（与该领域的其他长期研究合作）将为了解亚寒带食物网相互作用提供基础信息。